Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Wed, 18 Jul 1990 03:31:38 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 18 Jul 1990 03:31:01 -0400 (EDT) Subject: SPACE Digest V12 #86 SPACE Digest Volume 12 : Issue 86 Today's Topics: Journal of the Astro. Soc. of the Atlantic, Vol. I, No. XII Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription notices, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 16 Jul 90 18:06:50 GMT From: usc!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!emory!hubcap!mephisto!eedsp!chara!don@ucsd.edu (Donald J. Barry) Subject: Journal of the Astro. Soc. of the Atlantic, Vol. I, No. XII THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC Volume 1, Number 12 - July 1990 ########################### TABLE OF CONTENTS ########################### * ASA Membership/Article Submission Information * Viewing Jupiter's Galilean Moons with the Unaided Eye - Alan William Paeth * Gemini: The Celestial Twins - Michael S. Wiggs * The Flaws in the Hubble Space Telescope (HST) - From reports received by GSU astronomers ########################### ASA MEMBERSHIP INFORMATION The Electronic Journal of the Astronomical Society of the Atlantic (EJASA) is published monthly by the Astronomical Society of the Atlantic, Inc. The ASA is a non-profit organization dedicated to the advancement of amateur and professional astronomy and space exploration, and to the social and educational needs of its members. Membership application is open to all with an interest in astronomy and space exploration. Members receive the ASA Journal (hardcopy sent through U.S. Mail), the Astronomical League's REFLECTOR magazine, and may additionally purchase discount subscriptions to SKY & TELESCOPE, ASTRONOMY, DEEP SKY, and TELESCOPE MAKING magazines. For information on membership, contact the Society at: Astronomical Society of the Atlantic (ASA) c/o Center for High Angular Resolution Astronomy (CHARA) Georgia State University (GSU) Atlanta, Georgia 30303 U.S.A. asa%chara@gatech.edu or asa@chara.uucp ASA BBS: (404) 985-0408, 300/1200 Baud. or telephone the Society recording at (404) 264-0451 to leave your address and/or receive the latest Society news. ASA Officers and Council - President - Don Barry Vice President - Bill Bagnuolo Secretary - Ken Poshedly Treasurer - Alan Fleming Board of Advisors - Edward Albin, Jim Bitsko, Bill Hartkopf Council - Jim Bitsko, Julian Crusselle, Toni Douglas, Eric Greene, Larry Klaes, Becky Long, Max Mirot, Paul Pirillo, Patti Provost, Michael Wiggs ARTICLE SUBMISSIONS - Article submissions on astronomy and space exploration to the EJASA are most welcome. Please send your on-line articles in ASCII format to Larry Klaes, EJASA Editor, at the following net addresses or the above Society addresses: klaes@wrksys.enet.dec.com or - ...!decwrl!wrksys.enet.dec.com!klaes or - klaes%wrksys.dec@decwrl.enet.dec.com or - klaes%wrksys.enet.dec.com@uunet.uu.net You may also use the above net addresses for EJASA backissue requests, letters to the editor, and ASA membership information. Please be certain to include either a network or regular mail address where you can be reached, a telephone number, and a brief biographical sketch. DISCLAIMER - Submissions are welcome for consideration. Articles submitted, unless otherwise stated, become the property of the Astronomical Society of the Atlantic. Though the articles will not be used for profit, they are subject to editing, abridgment, and other changes. Copying or reprinting of the EJASA, in part or in whole, is encouraged, provided clear attribution is made to the Astronomical Society of the Atlantic, the Electronic Journal, and the author(s). This Journal is Copyright (c) 1990 by the Astronomical Society of the Atlantic. VIEWING JUPITER'S GALILEAN MOONS WITH THE UNAIDED EYE by Alan William Paeth As part of my being an amateur astronomer, I keep a personal challenge list of naked eye astronomical phenomena. Certain items, such as solar and lunar eclipses, are not difficult observations, but occur infrequently. Other events are exceedingly rare, such as occultations of naked eye stars by planetoids. But beyond these there are those "questionable" items which, rare or not, may not belong to this list: They may not be physically observable due to fundamental limitations of the human visual system. The observations of Jupiter's four Galilean moons - named for Galileo Galilei (1564-1642), who dis- covered them in 1610 - provide a prime example. While theoretically Io, Europa, Ganymede, and Callisto are just within the realm of unaided detection, there are few documented sightings of such events, despite such records going back to ancient China. Facts of Viewing Geometry - There are two observational difficulties in practice. First, the angular separation between the Galilean satellites and the primary (Jupiter) is small. Second, the large brightness differential of the system tends to mask the dimmer components. These optical conditions of resolving power and contrast relate to visual properties termed acuity and irradiation, respectively. These in turn are related to each satellite's distance from Jupiter, plus their respective visual magnitudes. We need only consider the Galilean satellites, as the next brightest Jovian satellite, Amalthea, is at magnitude +13.0 and represents a challenging object for the serious amateur using large instrumentation. The six brightest objects of the Jupiter system are tabulated below: Name Opposition Dist. (AU) Ang. Sep. Albedo Mean Magnitude Jupiter 5.203 --- 0.73 -2.6 Amalthea (V) 0.0012 1.0' --- 13.0 Io (I) 0.0028 2.4' 0.656 5.5 Europa (II) 0.0045 4.3' 0.715 5.7 Ganymede (III) 0.0072 6.3' 0.405 5.1 Callisto (IV) 0.0126 10.9' 0.266 6.3 Brightness figures are mean opposition values. Angular separation is based on the opposition of October, 1987, in which the distance between Earth and Jupiter dropped below four Astronomical Units (AU). One AU is the distance from the Sun to Earth's orbit, approximately 150 million kilometers (93 million miles). It is unfortunate that Callisto does not have a surface reflec- tance ratio (albedo) closer to the 70+ percent given for Jupiter or Ganymede, as this would give it a magnitude rivaling Ganymede with a larger angular spread. Fortunately, conditions of maximum brightness coincide with periods of maximum angular separation. This occurs near the time of opposition, when the Sun, Earth, and Jupiter lie in a rel- atively straight line. At this time the Jovian system is somewhat nearer (3.96 AU for October 17, 1987, plus or minus three days). The angular separation grows linearly with this decrease in distance. Brightness increases markedly because as the planetary disk grows linearly in size, its area (and brightness) grows as the square. Also, during opposition incident sunlight is retroreflected directly along the Earth-Sun line (albedo tends to decrease with increasingly oblique illumination angles). Unfortunately for observers, Jupiter has a high albedo and a cor- respondingly bright opposition magnitude, rivaling the planet Venus. A contrast ratio of 1000:1 is calculated based on a 7.4 difference in magnitude units. This is comparable to the thousandfold difference in contrast between fully transparent and fully opaque on photographic film. Would observation be better at periods other than opposition? No, because the brightness ratio between Jupiter and its satellites does not increase even at times when Jupiter is less dazzling. Instead, opposition observation yields the maximum possible angular separation and most importantly, brings the satellites' brightness beyond the threshold of detection for unaided vision. Idealized Conditions - The resolution limit of the human eye is often quoted as 1' (arc minute) of angular separation. The limiting magnitude is often put at six, with mid-fives being more characteristic under less than ideal seeing conditions. Theoretically, Ganymede alone with its angular separation of 6.3' should provide an adequate target, except for the mutual effect of retinal irradiation and small target separation. We might alternately consider the collection of Europa, taken at its maximum elongation yielding a 4.3' separation forming a coincident point image with Ganymede and Callisto. Of course, the points of light meet only in perspective, not in three dimensional space. The three then combine to yield a collective magnitude of 4.2 - easily visible under good conditions but at reduced separation versus Ganymede alone. The Attempt - In March of 1989 there was such a triple configuration of satellites in the early evening which prompted me to attempt the observation. With Jupiter "setting" in the west, the orbits (which run roughly parallel to the ecliptic) stood vertical to Earth's horizon, making it a simple matter to occlude (mask) the presence of Jupiter using distant power lines. As the apparent disk of Jupiter is roughly one-tenth the maximum Europa orbital distance, one can remove the planet without obscuring the satellites. Since Jupiter's diameter to distance ratio is roughly 5000:1, by using 6.25-millimeter (0.25- inch) thick power lines at thirty meters (one hundred feet), one can just cover the disc. In fact, halving this distance provides addi- tional overlap to insure complete coverage of Jupiter while accounting for minute head motion. But this has a liability: Because the dilated pupil is similar in size to a power line, it becomes possible for light rays to reach the edge of the eye's pupil on account of geometric par- allax - the observer is not watching from a dimensionless point. Far better is the use of larger, more distant objects, allowing for the same angular coverage while minimizing the effect of the observer's "aperture". After a frustrated thirty minutes of observing, I called it quits. As always, the moons were trivial to find in cheap 7x35 binoculars, and my 4x25 finder scope was just on the edge - chromatic aberration and all. I was sorely tempted to give up, concede failure, and quietly remove the line item from my naked eye observation list. But again, this was not a dark site, the planet was not near opposition, and there remained those stories. The scenario is most often a father pointing out Jupiter to his young daughter, who exclaims "Yes, Daddy, I see Jupiter! But what are those little stars right next to it?". As young observers typically possess the greatest resolving power (with an additional increase in acuity among women as well), these accounts possess an underlying shred of truth. To that add the Medieval accounts of rare sightings of "little stars swarming around Jupiter". Before retaining such a difficult item, however, I needed to confirm the possibility of observation. This would require a first-hand account - a big wish. The Wish - A few days later I got my wish. I had described my plight in an international electronic newsgroup connected to my university account, whose recipients were primarily other North American universities and scientific institutions. I was delighted when a reply was promptly returned by a fellow Alumni from the California Institute of Tech- nology (Caltech). Craig McCluskey worked for Hewlett-Packard in Colorado and provided just the confirmation I was seeking. What follows is a dialogue edited from our electronic transcripts. Paeth: What were the conditions when you managed to see a moon? McCluskey: Last fall on a clear, dry, Moonless night, I looked up at home (48 kilometers (thirty miles) east of Colorado Springs, elevation 2,088 meters (6,960 feet)) and saw slightly west of Orion what I was later to learn was Jupiter. I said to myself, "That's not an ordinary star, there's something beside it." So I went inside and got my 10x50 binoculars and took a second look. Sure enough, there was something there (on Jupiter's left side) and I was able to make out enough of the [atmosphere] bands to tell it was Jupiter. Having used the one-tenth scale proof-model of the Palomar fifty-centimeter (twenty-inch) telescope that was at Caltech to look at Jupiter while I was a student there in 1970, I was familiar enough with what Jupiter looks like to recognize it. Paeth: Assuming you confirmed the sighting on a celestial calendar, were you seeing Ganymede itself at large separation, or a brighter collection of moons at a reduced separation? McCluskey: I don't know what the positions of the moon were then. Nor, unfortunately, do I recall the exact date. Paeth: Also, is your night vision or visual acuity (resolving power) unusually good? For instance, can you routinely see more than six [stars] of the Pleiades? (Maybe I should observe in the Rockies!) McCluskey: I haven't been aware that my night vision nor visual acuity are unusually good. I wasn't trying to see how many of the Pleiades I could see when I looked at them closely last fall, so I don't recall how many of them I saw. I haven't stayed outside long enough at night lately for my eyes to completely dark adapt (it's cold!), so I haven't repeated that observation. I do know that I can see M31 [Messier 31, the Andromeda Galaxy], though. Paeth: Thanks for the update. McCluskey: From one ex-Caltecher to another, no problem! Craig The Challenge - In conclusion, I now believe that Jupiter's moons have earned a right to occupy a place on my naked eye wish list. The Royal Astronomical Society of Canada (RASC) Handbook, along with ASTRONOMY and SKY & TELESCOPE magazine, give monthly tables of Jovian satellite orbital configurations listed on an hour-by-hour basis. So plan an evening, study the tables, and then start observing. Hopefully my efforts will assist you in finding the moons of Jupiter with your unaided eyes. Such projects are also useful in helping you become more experienced at astronomical observation. Suggested Readings on the Galilean Moons - Baugher, Joseph F., THE SPACE-AGE SOLAR SYSTEM, John Wiley and Sons, Inc., New York, 1988 Briggs, G. A. and F. W. Taylor, THE CAMBRIDGE PHOTOGRAPHIC ATLAS OF THE PLANETS, Cambridge University Press, New York, 1988 Hartmann, William K., and Ron Miller, THE GRAND TOUR: A TRAVELER'S GUIDE TO THE SOLAR SYSTEM, Workman Publishing Co., Inc., New York, 1981 Morrison, David (Editor), SATELLITES OF JUPITER, The University of Arizona Press, Tucson, 1982 About the Author - Alan Paeth is a doctoral candidate in the department of Computer Science at the University of Waterloo, Ontario, Canada, specializing in Computer Graphics. Previously, Alan was a research scientist with Xerox PARC. An active amateur since the late 1960s, he was president of the Kitchener-Waterloo chapter of the Royal Astronomical Society of Canada (RASC) during 1989. He is married and has two children. GEMINI: THE CELESTIAL TWINS by Michael S. Wiggs Soaring high in the winter night is the ancient constellation of Gemini the Twins. Its two brightest stars, separated by a mere 4.5 degrees, represent the two brothers of Greek myth, Castor and Pollux. According to one of several legends passed down to us through the centuries, Castor and Pollux were sons of the chief Greek god Zeus. Of the two, only Pollux was immortal. When Castor eventually died, Pollux was so overwhelmed with grief and sorrow that he wanted to share his immortality with his beloved brother. Their father, Zeus, rejoined them by situating the two next to each other in the heavens. Located nearly overhead at northern latitudes during winter nights, Gemini is easily observed just to the north and east of the red giant star Betelgeuse in the constellation of Orion the Hunter. In this locale of Earth's sky, one finds the Starry Twins, named so for their similarity in brightness. Castor ("The Horseman"), or Alpha Geminorum, the fainter and northernmost of the two, shines at roughly magnitude +1.5, and is a brilliant white star placed nearly forty-five light years from Earth. Castor is a striking double star for medium-sized telescopes, appearing as two splendid diamonds in the sky. This star, parenthetically, was the first object beyond our solar system to be recognized as a system bound by gravity, revolving around each other in the depths of space. Surprisingly, each of the two bright stars of Castor are also double, making a total of four stars. These are too close to be separated in average telescopes. There is also another star in this system, a faint red dwarf star which is also a binary, making a grand total of six stars in this remarkable and complex system. Pollux (Greek for "Boxer" or "Pugilist"), or Beta Geminorum, the brighter of the Twins, is just a bit to the south. Shining at magnitude +1.16, Pollux is the seventeenth brightest star in the night sky. Lying nearly thirty-five light years from Earth, Pollux is a yellowish star about eleven times larger than our Sun. South of Castor are two stars of similar magnitude known as the foot of Castor. Constructing a line from the star Mu Geminorum to Castor, one will find the star Mebsuta (Epsilon Geminorum), which is essentially the body of Castor. Moving to the star Pollux, a similar line of stars can be constructed parallel to the ones of Castor, which represent the body of Pollux. This nearly straight line will run from Pollux through Wasat (Delta Geminorum) and end at Alhena (or Almeisam, also called Gamma Geminorum), marking the feet of Pollux. Gemini offers several deep sky objects of interest to the owners of binoculars and telescopes. The most splendid of these is the magnificent open star cluster Messier 35 (M35). Located about two degrees northwest of Propus (Eta Geminorum) at the foot of Castor, M35 can be glimpsed as a hazy patch of light to the unaided eye under dark conditions, away from city lights and with no interference from the Moon. While small telescopes will hint at the splendor of M35, it is best viewed in a fifteen-centimeter (six-inch) or larger telescope at low power, where it will appear as an explosion of tiny jewels suspended in the darkness. Containing more that three hundred stars, this group lies at least 2,200 light years distant, with a diameter of approximately thirty light years. Immediately to the southwest of M35 and in the same field of view in low power eyepieces, one can see another open cluster, NGC 2158. This cluster appears as a fuzzy cloud in fifteen-centimeter (six-inch) instruments due to its extreme distance, roughly sixteen thousand light years from Earth. Only very large amateur telescopes can resolve this rich cluster into its individual stars, but it is quite noticeable in smaller telescopes. M35 and NGC 2158 make a fine pair for medium-sized objectives. If you have such an instrument and enjoy open clusters, try for NGC 2129, located about one degree due west of the binary star 1 Geminorum. This is a small cluster of about fifty stars that is easy to find and well worth a look. For observers who are experienced at "star-hopping", or who have setting circles, try for a few other small open clusters: NGC 2304 (06h 53m, 18-05N), which contains about twenty faint stars; NGC 2420 (07h 36m, 21-41N), and NGC 2266 (06h 41m, 27-02N), both of which are relatively faint. We now turn our attention to a fascinating object, a planetary nebula. These objects derive their name from the fact that through the telescope they look like small, distant planets; but in reality they are not planets at all. They are spheres of gas surrounding a dwarf star that has thrown off this material at the end of its nuclear burning stage. A planetary nebula represents the death of a star, a quiet demise not to be confused with the violent phenomena of super- novae, where stars are ripped apart by tremendous releases of energy and matter. NGC 2392 is a bright planetary first discovered by William Herschel (1738-1822) in 1787. This nebula is easily found by first searching for the star Wasat, then moving about two degrees due east to the star 63 Geminorum, the brightest of a small group of three stars. Looking about two-thirds of a degree southeast of 63 Geminorum, using moderate power eyepieces, one will observe a greenish, fuzzy glow that is distinctly non-stellar in appearance. This object is sometimes known as the Eskimo Nebula, for in very large telescopes a faint outer ring is visible, resembling the hood of a parka. This similarity is quite striking on long exposure photographs. Another planetary, though faint at magnitude +12.5, is NGC 2371/72, which appears double due to its ends, which are brighter than the center. It is best suited for the enthusiastic observer with setting circles. Gemini also contains an example of an interesting and important class of variable stars: Zeta Geminorum, located in the "body" of Pollux, is a Cepheid variable and is one of the brightest of this type in the sky. Rising from about fifth up to nearly fourth magni- tude, Zeta Geminorum has a period of just over ten days. Cepheids are pulsating stars whose luminosity and pulsation period are inti- mately related, thus allowing its distance from us to be determined with a fair degree of accuracy. The presence of Cepheids in other galaxies millions of light years away are quite useful in knowing their distances. Zeta Geminorum was discovered by J. Schmidt in the late 1840s and is located nearly 1,500 light years from Earth. This concludes the brief treatise on the Starry Twins. Armed with this information and some good star maps, you will be well prepared to go out and enjoy the celestial wonders of Gemini! References and Further Reading: Allen, Richard H., STAR NAMES: THEIR LORE AND MEANING, Dover Books, New York, 1963 (1899) Burnham Jr., Robert, BURNHAM'S CELESTIAL HANDBOOK (three volumes), Dover Books, Mineola, New York, 1978 Menzel, Donald H., and Jay M. Pasachoff, FIELD GUIDE TO THE STARS AND PLANETS, Houghton Mifflin Company, Boston, 1983 Staal, Julius D. W., THE NEW PATTERNS IN THE SKY, McDonald and Woodward, Blacksburg, 1988 About the Author - Michael Wiggs, Co-Chairman of the ASA Observatory Committee, is pursuing advanced study in astronomy at Georgia State University (GSU). An active amateur, Mike is interested in telescope construction and observing. His professional interests include interacting hot binary stars, stellar formation, stellar spectroscopy, and cosmology. Michael is also the author of "Orion: Winter's Mighty Hunter", in the December 1989 issue of EJASA. THE FLAWS IN THE HUBBLE SPACE TELESCOPE (HST) From reports received by GSU astronomers The week of June 22, 1990, may be long remembered by astronomers as a time of disappointment as National Aeronautics and Space Admini- stration (NASA) scientists determined that the optics aboard the 2.1 billion dollar Hubble Space Telescope (HST) were seriously flawed. During two months of testing following the satellite's launch into Earth orbit in late April of 1990 aboard the Space Shuttle DISCOVERY (STS-31), puzzling results were obtained during the slow activation process as tests were made to slowly collimate and power on the various subsystems of the complex "sky observatory". Starting in late June, a series of special tests were commanded to measure the shape of star images taken inside and outside of the focus point of the mirror assembly. Although these mirrors were built using the latest technology, and are thought to be the most accurate optical surfaces ever figured, the pictures from Hubble's Wide-Field Planetary Camera (WFPC) revealed that although the mirror surfaces were carefully made, they were made wrong. This is a clear example of the scientific distinction between "precision" and "accuracy". It is not yet known which of the two mirrors in Hubble is incorrect, though several scientists associated with Hubble have speculated that the secondary mirror is at fault. The primary mirror, with a hyperboloidal figure similar to that of the Fernbank Science Center's 90-centimeter (36-inch) Tinsley reflector, was figured by the Perkin-Elmer Corporation using the latest computer technology. The secondary, also made by Perkin-Elmer, is a convex mirror, and could only be tested in conjunction with a concave optic. Because errors in the test mirror used with the secondary could have affected the figure of the secondary mirror, it is possible that a small numerical error could have passed by the variety of quality controls imposed, only to show up during final operation. Although many individual subsystems of Hubble were tested before assembly, there was never a test performed of the total optical assembly, using both mirrors together. Jean Olivier, Deputy Project Manager for Hubble at the Marshall Space Flight Center, was quoted as stating that to test the entire unit would have required construction of special facilities costing hundreds of millions of dollars. However, United States Air Force (USAF) facilities already exist of this sort, and are used to test their large-aperture "spy satellites", many which are rumored to have mirrors as large as Hubble's. The affect on Hubble's performance is astonishing. Light striking the combination of mirrors is given a displacement over one-half wavelength in error, whereas original specifications called for an optical figure error of less than 1/60 wavelength in each mirror. Star images are therefore seen as small blurs about one arcsecond in size, rather than the 0.07 arcsecond originally expected. This image size is more typical of Earth-based telescopes under good seeing than space-based instruments. The error affects each of the five scientific instruments aboard the telescope, although some are affected to a greater degree than others. Principal Investigator of the Wide Field Planetary Camera (WFPC), James Westphal, has announced that his camera will be essen- tially useless with the telescope in its current state. The European- built Faint Object Camera (FOC) will also yield aberrated images. The two instruments can therefore only yield results about as good as that obtained with ground-based telescopes, though they will be able to look at the Universe in ultraviolet and infrared wavelengths invisible from Earth. These waves are normally blocked out by Earth's atmosphere. The Michigan-built High Speed Photometer (HSP) will also suffer, because it will not be possible to direct all of the light of a star or other celestial object through the small entrance apertures of the instrument. Slight shifts in the telescope's position might therefore mimic variations in intensity of the object under study, rendering the data valueless. The two remaining instruments, both spectrographs, will suffer least from the telescope's performance. The Goddard High Resolution Spectrograph (HRS) normally accepts light from a 0.1 arcsecond aperture, but does not otherwise use the imaging capability of the telescope. Because only a fraction of the light will fall in such a small aperture, the spectrograph will operate at reduced efficiency, but will be otherwise unimpaired. The Faint Object Spectrograph (FOS) usually operates with a larger entrance aperture and will be least affected. An investigating panel has been named by NASA to find out how this fault escaped notice. Logbooks and other materials at Perkin-Elmer have been impounded, but it may take weeks before the erroneous trail of calibration and test data is located. NASA scientists believe that if the mirror figures can be suffici- ently determined, either through observations with the telescope, or through careful study of engineering notebooks, that second generation instruments can be designed with additional optics to correct for the aberrations introduced in the main Hubble optical system. These instruments, which will not be ready before 1993, could therefore perform near the Hubble Space Telescope's original design goals. THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC July 1990 - Vol. 1, No. 12 Copyright (c) 1990 - ASA -- Donald J. Barry (404) 651-2932 | don%chara@gatech.edu Center for High Angular Resolution Astronomy | President, Astronomical Georgia State University, Atlanta, GA 30303 | Society of the Atlantic ------------------------------ End of SPACE Digest V12 #86 *******************